/* ==========================================
 * JGraphT : a free Java graph-theory library
 * ==========================================
 *
 * Project Info:  http://jgrapht.sourceforge.net/
 * Project Creator:  Barak Naveh (http://sourceforge.net/users/barak_naveh)
 *
 * (C) Copyright 2003-2006, by Barak Naveh and Contributors.
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */
/* --------------------
 * PerformanceDemo.java
 * --------------------
 * (C) Copyright 2003-2006, by Barak Naveh and Contributors.
 *
 * Original Author:  Barak Naveh
 * Contributor(s):   -
 *
 * $Id: PerformanceDemo.java,v 1.2 2007/05/22 15:52:59 kjellw Exp $
 *
 * Changes
 * -------
 * 10-Aug-2003 : Initial revision (BN);
 *
 */
package org.jgrapht.demo;

import java.io.*;

import java.util.*;

import org.jgrapht.*;
import org.jgrapht.graph.*;
import org.jgrapht.traverse.*;

/**
 * A simple demo to test memory and CPU consumption on a graph with 3 million
 * elements.
 * 
 * <p>
 * NOTE: To run this demo you may need to increase the JVM max mem size. In
 * Sun's JVM it is done using the "-Xmx" switch. Specify "-Xmx300M" to set it to
 * 300MB.
 * </p>
 * 
 * <p>
 * WARNING: Don't run this demo as-is on machines with less than 512MB memory.
 * Your machine will start paging severely. You need to first modify it to have
 * fewer graph elements. This is easily done by changing the loop counters
 * below.
 * </p>
 * 
 * @author Barak Naveh
 * @since Aug 10, 2003
 */
public final class PerformanceDemo {
	// ~ Methods
	// ----------------------------------------------------------------

	/**
	 * The starting point for the demo.
	 * 
	 * @param args
	 *            ignored.
	 */
	public static void main(String[] args) {
		long time = System.currentTimeMillis();

		reportPerformanceFor("starting at", time);

		Graph<Object, DefaultEdge> g = new Pseudograph<Object, DefaultEdge>(
				DefaultEdge.class);
		Object prev;
		Object curr;

		curr = prev = new Object();
		g.addVertex(prev);

		int numVertices = 10000;
		int numEdgesPerVertex = 200;
		int numElements = numVertices * (1 + numEdgesPerVertex);

		System.out.println("\n" + "allocating graph with " + numElements
				+ " elements (may take a few tens of seconds)...");

		for (int i = 0; i < numVertices; i++) {
			curr = new Object();
			g.addVertex(curr);

			for (int j = 0; j < numEdgesPerVertex; j++) {
				g.addEdge(prev, curr);
			}

			prev = curr;
		}

		reportPerformanceFor("graph allocation", time);

		time = System.currentTimeMillis();

		for (Iterator i = new BreadthFirstIterator<Object, DefaultEdge>(g); i
				.hasNext();) {
			i.next();
		}

		reportPerformanceFor("breadth traversal", time);

		time = System.currentTimeMillis();

		for (Iterator i = new DepthFirstIterator<Object, DefaultEdge>(g); i
				.hasNext();) {
			i.next();
		}

		reportPerformanceFor("depth traversal", time);

		System.out
				.println("\n"
						+ "Paused: graph is still in memory (to check mem consumption).");
		System.out.print("press any key to free memory and finish...");

		try {
			System.in.read();
		} catch (IOException e) {
			e.printStackTrace();
		}

		System.out.println("done.");
	}

	private static void reportPerformanceFor(String msg, long refTime) {
		double time = (System.currentTimeMillis() - refTime) / 1000.0;
		double mem = usedMemory() / (1024.0 * 1024.0);
		mem = Math.round(mem * 100) / 100.0;
		System.out.println(msg + " (" + time + " sec, " + mem + "MB)");
	}

	private static long usedMemory() {
		Runtime rt = Runtime.getRuntime();

		return rt.totalMemory() - rt.freeMemory();
	}
}

// End PerformanceDemo.java
